Delivery system for endoluminal implant

ABSTRACT

A delivery system for delivering an endoluminal implant to a distal deployment location inside a body lumen from a proximal access location outside the lumen. The system comprises the implant, a catheter, and a slidable sheath having an advanced position in which the sheath covers the implant and a retracted position in which the implant is exposed. The catheter comprises a stabilizer having a distal end adjacent the implant proximal end and/or a catheter tip attached to a central core slideably disposed relative to the implant and having a proximal end adjacent the implant distal end. The catheter tip proximal end and/or the stabilizer distal end comprises a docking section adapted to releasably engage a portion of the implant. Each docking section has an engagement geometry comprising a flared engagement surface that extends inside a short axial length of the implant or a pocket having a bottleneck geometry.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/573,273, filed May 18, 2000, which claims priority from U.S.Provisional Patent Application Serial No. 60/134,971, filed on May 20,1999, both of which are herein incorporated by reference.

TECHNICAL FIELD

The present invention relates generally to endoluminal grafts or“stents” and, more specifically, to stent delivery systems or“introducers”.

BACKGROUND OF THE INVENTION

A stent is an elongated device used to support an intraluminal wall. Inthe case of a stenosis, a stent provides an unobstructed conduit forblood in the area of the stenosis. Such a stent may also have aprosthetic graft layer of fabric or covering lining the inside oroutside thereof, such a covered stent being commonly referred to in theart as an intraluminal prosthesis, an endoluminal or endovascular graft(EVG), or a stent-graft. As used herein, however, the term “stent” is ashorthand reference referring to a covered or uncovered such stent.

A stent may be used, for example, to treat a vascular aneurysm byremoving the pressure on a weakened part of an artery so as to reducethe risk of rupture. Typically, an intraluminal stent is implanted in ablood vessel at the site of a stenosis or aneurysm endoluminally, i.e.by so-called “minimally invasive techniques” in which the stent,restrained in a radially compressed configuration by a sheath orcatheter, is delivered by a stent deployment system or “introducer” tothe site where it is required. The introducer may enter the body throughthe patient's skin, or by a “cut down” technique in which the entryblood vessel is exposed by minor surgical means. When the introducer hasbeen threaded into the body lumen to the stent deployment location, theintroducer is manipulated to cause the stent to be ejected from thesurrounding sheath or catheter in which it is restrained (oralternatively the surrounding sheath or catheter is retracted from thestent), whereupon the stent expands to a predetermined diameter in thevessel into the deployment location, and the introducer is withdrawn.Stent expansion may be effected by spring elasticity, balloon expansion,or by the self-expansion of a thermally or stress-induced return of amemory material to a pre-conditioned expanded configuration.

Referring now to FIGS. 1A and 1B, there is shown a prior art, pre-loadedstent delivery system 10 for housing and deploying a compressed stent14. Stent delivery system 10 comprises an outer sheath 12 and aconventional pusher or stabilizer 16 loaded proximal to the stent. Asused herein, the term “proximal” refers to the end closer to an accesslocation outside the body whereas “distal” refers to the farther fromthe access location. Delivery system 10 also typically comprises acatheter tip 20 at the distal end and a pusher handle 25 located at theproximal end outside the body lumen. The catheter tip may be attached tocentral core 23 that runs through central lumen 22 within pusher 16.Central core 23 may guide the delivery system through the body lumenover a guidewire (not shown) to the area to be repaired, or may beadapted for inflating a balloon (if applicable), and/or for flushing thesystem. The delivery system may additionally have radiopaque markers atselected locations therein to be used for fluoroscopic guidance of thesystem through the body lumen.

To deploy stent 14, delivery system 10 is threaded through the bodylumen to the desired location for stent deployment. Outer sheath 12 isthen retracted, and pusher 16 acts as a stabilizer to keep stent 14 fromretracting with the sheath. As outer sheath 12 retracts, stent 14 isexposed and expands into place against the body lumen to be repaired.The stent may be a self-expanding stent, such as a stent made ofshape-memory nitinol (nickel-titanium) wire as are well-known in theart, or the stent may require inflation of a balloon to expand itagainst the walls of the body lumen, as is also well-known in the art.

Regardless of the type of stent or delivery system, the portion ofdelivery system 10 that houses compressed stent 14 typically hasincreased mass and rigidity as compared to the rest of delivery system10. Thus, referring now to FIG. 2, when introducing delivery system 10through tortuous anatomy, kinking of the delivery system may occur inregion 17 of the system where pusher 16 and stent 14 interface, due tothe rigidity of both the stent and the pusher. Kinking along kink angle“a” may develop as a result of the rigidity of compressed stent 14,whereas kinking along kink angle “b” may develop as a result of therigidity of pusher 16. The resulting kink angle a+b is thereforedependent upon the material properties of both the compressed stent 14and pusher 16. Similar kinking may also occur in region 18 where stent14 and tip 20 interface.

Such kinking may prevent or hamper proper deployment of stent 14 becausecreases 15 that develop where sheath 12 is bent may prevent retractionof the sheath. Such creases 15 present a problem not only where stent 14is intended for deployment in the tortuous portion of the body lumen,but also may persist even after the delivery system 10 is ultimatelynavigated past the tortuous portion of the lumen to a remote deploymentsite. Also, the discontinuity of the contact surface between stent 14and pusher 16 could lead to an improper or inaccurate deployment of thestent. Where kinking causes such creases 15 in sheath 12 that preventdeployment, delivery system 10 must be retracted from the body anddiscarded, and the introduction process must start again with a newintroducer. Thus, there is a need in the art to prevent such kinking instent delivery systems.

SUMMARY OF THE INVENTION

One aspect of the invention comprises a delivery system for delivering aendoluminal implant to a distal deployment location inside a body lumenfrom a proximal access location outside the body lumen. The deliverysystem comprises the implant having a proximal end and a distal end; acatheter comprising at least one of a stabilizer having a distal endlocated adjacent the implant proximal end, a catheter tip attached to acentral core slideably disposed relative to the implant and having aproximal end located adjacent the implant distal end, or a combinationthereof; and a slidable sheath having an advanced position in which thesheath covers the implant and a retracted position in which the implantis exposed. At least one of the catheter tip proximal end or thestabilizer distal end comprises a docking section adapted to releasablyengage a portion of the implant, each docking section comprising anengagement geometry for engaging the implant, each docking sectionengagement geometry comprising a flared engagement surface that extendsinside a short axial length of the implant or a pocket having abottleneck geometry.

Another aspect of the invention comprises a system for retaining aportion of a medical implant on a delivery member until performance of apredetermined release action. The system comprises the delivery member,comprising an outer sheath and an inner tubular member for engaging aportion of the implant, the sheath having an advanced position in whichthe sheath covers the implant, and a retracted position in which theimplant is exposed. The inner tubular member has an axis and one or moreflexible fingers, the one or more flexible fingers having anunrestrained configuration with the sheath in the retractedconfiguration in which the fingers are biased angularly outward from theinner tubular member axis, and a restrained configuration with thesheath in the advanced configuration in which the fingers are adapted toengage a portion of the implant. Each finger comprises an end memberhaving a different cross sectional geometry than a remainder of thefinger.

Yet another aspect of the invention comprises a delivery system fordelivering an endoluminal implant, the delivery system comprising theimplant having a proximal end and a distal end and a catheter comprisingat least one of a stabilizer, a catheter tip, or a combination thereof,the stabilizer having a distal end located adjacent the implant proximalend, the catheter tip having a proximal end located adjacent the implantdistal end and attached to a central core slideably disposed relative tothe implant. At least one of the catheter tip proximal end or thestabilizer distal end comprises a docking section adapted to releasablyengage a portion of the implant, the docking section comprising a pocketadapted to releasably contain a limited length of one end of thecompressed implant inserted therein. The pocket comprises an annularpocket having an inner wall located radially inward of the compressedimplant and an outer wall located radially outward of the compressedimplant, the inner wall and the outer wall both terminating at asubstantially same axial location relative to the implant.

Still another aspect of the invention comprises a delivery systemcomprising the implant; a catheter comprising at least one of astabilizer having a distal end located adjacent the implant proximal endand/or a catheter tip attached to a central core slideably disposedrelative to the implant and having a proximal end located adjacent theimplant distal end; and a slidable sheath having an advanced position inwhich the sheath covers the implant and a retracted position in whichthe implant is exposed. At least one of the catheter tip proximal end orthe stabilizer distal end comprises a docking section adapted toreleasably engage a portion of the implant, the docking sectioncomprising an engagement geometry for engaging the implant, in which thedocking section engagement geometry comprises (a) a pocket having anouter wall located radially outward of the compressed implant and (b) aradial protrusion that engages the implant. In one embodiment, thedocking section radial protrusion protrudes inward from the pocket outerwall. In another embodiment, the docking section pocket comprises aflared end rim radially biased outward relative to the compressed stentand adapted for the inward protrusion to releasably grip a limitedlength of the proximal end of the stent in pushing engagement therewithwhen the flared end rim is inwardly compressed by the sheath to anon-flared diameter.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the invention.

BRIEF DESCRIPTION OF DRAWING

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawing. It is emphasizedthat, according to common practice, the various features of the drawingare not to scale. On the contrary, the dimensions of the variousfeatures are arbitrarily expanded or reduced for clarity. Included inthe drawing are the following figures:

FIG. 1A is a longitudinal section schematic illustration of an exemplarystent delivery system of the prior art.

FIG. 1B is an enlarged portion of FIG. 1A.

FIG. 2 is a longitudinal section schematic illustration of an exemplarystent delivery system of the prior art in a kinked state due to thevarying rigidity along the system.

FIG. 3 is a longitudinal section schematic illustration of a portion ofan exemplary stent delivery system of the present invention, showing thestent in a compressed state cradled in the docking section pockets ofboth the catheter tip and the pusher.

FIG. 4 is a longitudinal section schematic illustration of the pusher ofFIG. 3 shown in a deployed state after retraction of the outer sheath.

FIG. 5 is a flowchart depicting an exemplary method of deploying a stentin accordance with the present invention.

FIG. 6 a longitudinal section schematic illustration of exemplarydocking sections of the present invention, showing the stent in acompressed state with a pusher docking section and a catheter dockingsection inserted in the ends thereof.

FIG. 7A and 7B are an end view and a side view, respectively, of anexemplary docking section of the present invention comprising a set offingers.

FIGS. 8A and 8B are an end view and a side view, respectively, of anexemplary docking section of the present invention comprising an annularpocket.

FIG. 8C is an end view of an exemplary docking section of the presentinvention, showing a docking section comprising an annular pocketdefined by a plurality of fingers.

DETAILED DESCRIPTION OF INVENTION

Referring now to the drawing, wherein like reference numerals refer tolike elements throughout, FIGS. 3-4 illustrate an exemplary stentdelivery system 10′ of the present invention, having an exemplarydocking pusher 16′ and docking catheter tip 20′. As shown in FIG. 3,stent delivery system 10′ comprises an outer sheath 12, central lumen22, and central core 23, similar to delivery systems known in the art.As used herein, the term “system” shall encompass both a completedassembly which is capable of deploying a stent or a sub-assembly whichis capable of deploying a stent when combined with other components.Docking pusher 16′ and catheter tip 20′, however, comprise dockingsections 42 and 42′ respectively, each docking section having a pocket40 and 40′, respectively. Docking section 42 located at pusher distalend 28 is adapted to hold proximal end 30 of compressed stent 14,whereas docking section 42 located at catheter tip proximal end 29 isadapted to hold distal end 31 of compressed stent 14. Docking section 42or 42′ may be a discrete section connected to, respectively, pusher 16′or catheter tip 20′, as shown in FIGS. 3 and 4 with respect to pusher16′, or may be a hollowed section integral to the rest of the pusher orcatheter tip, as shown in the figures with respect to catheter tip 20′.Other docking section configurations or means for engaging thecompressed stent end with the pusher or catheter tip may also be used,as described herein later.

The term “pusher” is used herein throughout, although such device mayalso be referred to in the art as a “stabilizer”, because the method ofdeploying the stent may not actually comprise “pushing” the stent out ofthe sheath, but rather “stabilizing” the stent (holding it in place andpreventing it from moving) while the outer sheath is retracted. Thus,use of the term “pusher” herein refers to such a device adapted for anymethod of deploying known in the art, including as a stabilizer, and theterm “pusher” is not intended as a limitation thereof.

Docking pusher 16′ and docking catheter tip 20′ overcome kinking in thebody lumen because a certain amount of compressed stent 14 is actuallydocked or cradled inside pocket 40 or 40′, creating a smooth transitionbetween the stent and the pusher or catheter tip. The pusher and stentand/or catheter tip and stent in such docked configurations thus movetogether at their respective interface points while navigating thetortuous anatomy of the body lumen, by minimizing any area of weakenedrigidity to prevent kinks.

In addition, as long as rim 44 of docking section 42 in pusher 16′ gripsstent 14, the stent may be “recaptured” or “recovered” even once it hasbeen partially deployed. For instance, if a medical professionaldetermines that a partially deployed stent 14 needs to be repositioned,pusher 16′ may be pulled back within sheath 12 or the sheath advanced torecover the partially deployed stent. Then, the deployment process canstart over. Other embodiments having other means for releasably engagingthe stent may offer similar recapture capabilities.

Also, because of the docked arrangement between stent 14 and pusher 16′,the stent may be rotated, pushed, or pulled both before and duringdeployment, unlike with conventional deployment systems where the pushercan only transmit force in a pushing direction. For example, where thestent architecture has a particular feature intended for alignment witha particular part of the body lumen, such as a particularly flexibleportion of the stent to be aligned with a tortuous portion of the bodylumen, the stent can be rotated, pushed, or pulled to effect thisalignment. Additionally, in the configuration shown in FIG. 3 wheredocking section 42 pinches stent 14 against central core 23, creatingfriction, there is less undesired movement of the stent inside thedelivery system as compared to non-docked prior configurations.Additionally, the use of a docking section in the catheter tip mayfacilitate placement of the distal end of the stent in a predeterminedlocation.

As shown in FIG. 3, stent 14 is held within pocket 40 of docking section42 of pusher 16′ and pinched inwardly by end rim 44. When compressedwithin sheath 12, docking section 42 has a bottleneck shape created byinward protrusions 48 of end rim 44 that define a neck with a smallerdiameter than the remainder of pocket 40, as shown in FIG. 3. End rim 44of docking section 42 thus has a normal radial bias outward that iscompressed and confined within the walls of sheath 12 duringintroduction to the body. As shown in FIG. 4, once the target zone hasbeen reached, outer sheath 12 is retracted. When sheath 12 is retractedbeyond end rim 44 of docking section 42, rim 44 springs open into anoutwardly flared configuration and releases proximal end 30 of stent 14.Accordingly, docking section 42 may comprise any material, such asstainless steel, that provides flared end rim 44 with the requisite“springiness” to pinch inward when compressed and to spring open whenthe sheath is retracted. Although illustrated with respect to the pusherdocking section 42 in FIG. 4, this outwardly-flared configuration mayalso be applicable to catheter tip docking section 42′; however, asshown in FIG. 3, a non-outwardly-biased, cylindrical configuration ispreferred, as described below.

Instead of having a bottleneck shape when compressed within sheath 12and radially flared and biased outward when not housed within thesheath, end rim 44′ of docking section 42′ in catheter tip 20′ iscylindrical in shape and capable of holding stent 14 within pocket 40′merely by frictional engagement. Prior to retraction of sheath 12 todeploy stent 14, central core 23 and tip 20′ attached thereto may, insome cases, need to be advanced distally so that the stent disengagesfrom the pocket 40′. Such a non-radially-biased pocket may also beprovided on docking section 42 of pusher 16′. In such case, stent 14 maybe partially deployed and anchored into the walls of a body lumen sothat the stent has sufficient frictional resistance against the bodylumen to enable pusher 16′ to be retracted to disengage the stent fromwithin the non-flared pocket without dislocating the stent.

The step of advancing catheter tip 20′ prior to retraction of sheath 12may also be performed to facilitate stent delivery even where dockingsection 42′ includes a radially-biased end rim (not shown). Such aradially-biased end rim on catheter tip 20′, however, may presentdifficulty in preparing delivery system 10′ for retraction from the bodyafter deployment unless there is some mechanism to re-compress the endrim back inside sheath 12. Without such re-compression of theradially-biased end rim back inside the sheath, such as is possible withrespect to pusher 16′ merely by retracting the pusher to pull end rim 44back inside sheath 12, the radially-biased end rim may protrude from thestreamlined shape of the delivery system at the catheter end duringretraction and provide a catching point that may damage the body lumen.Thus, a non-radially-biased end rim 44′ is preferred for catheter tip20′.

Docking section 42 may include a radiopaque marker 46, to provideincreased radiographic “vision” of the pusher end, and when combinedwith a similar marker (not shown) on the proximal end of stent 14, tovisualize relative movement of pusher and stent as stent 14 disengagesfrom pusher 16′. Similar markers 46 may also be provided for similarpurposes on the catheter tip docking section 42′ and on the stent distalend (not shown). “Radiopaque marker” as used herein encompasses anydiscrete area of different radiopacity as compared to a surroundingarea.

Pusher docking sections, catheter tip docking sections, stent deliverysystems, and methods incorporating such pushers and/or catheter tips maytake a wide variety of forms other than that described specificallyabove. A particular stent delivery system may include only a pusherdocking section, only a catheter tip docking section, or both. Theessence of any such docking section is that it releasably engages an endof the stent over some axial length in a manner whereby that engagementis releasable upon stent deployment. The term “releasably engaging”denotes that the engagement between the docking section and the stent isnot permanent, but rather is releasable in the sense that the stent isreleased from the docking section when the outer sheath is retracted orwhen the pusher or catheter tip is advanced or retracted away from thestent. The pusher docking section is either biased radially outward ordefines a pocket in which the portion of the stent proximal end isnested.

The length of the stent engaged by the docking section of this inventionshould be sufficiently long, taking into account the stent diameter andflexibility as well as the tortuosity of the lumen to be traversedduring its deployment, to maintain a pushing engagement notwithstandingthe tortuosity for which the stent is designed. Such pushing engagementenables transmission of a pushing force applied thereto, such as fromthe pusher to the stent, or from the stent to the catheter tip. Thelength of the stent engaged by the docking section should besufficiently short, however, and/or the angle of radial flare a (asshown in FIG. 4) sufficiently great, so as to facilitate reliablerelease of stent 14 when sheath 12 is retracted. The dimensions andmechanical features of individual docking section designs may be readilydeterminable by those skilled in the art.

In particular, the docking section may comprise an axially-extendingengagement surface which extends over a short axial length of the stenteither on the interior or exterior thereof. Such surface may define theinterior of pocket 40 previously described and shown in FIGS. 3 and 4,or an insert adapted to be inserted within the stent end to engage thestent end, as shown in FIG. 6.

As shown in FIG. 6, docking section 142′ of catheter tip 120 is areduced diameter section (i.e., an insert) of catheter 120 that fitswithin distal end 31 of compressed stent 14. Docking section 142 ofpusher 116 fits within proximal end 30 of compressed stent 14, and isradially biased outward to firmly hold stent 14 against sheath 12. Suchbias outward to radially urge the stent proximal end 29 against theinner surface of the deployment sheath 12 further facilitates pusher 116and stent 14 moving as one without pulling away from one another.Although docking section 142′ having merely a reduced diameter sectionis illustrated in FIG. 6 with respect to catheter tip 120 whereasradially-biased-outward docking section 142 is illustrated with respectto pusher 116, either configuration is applicable to both the cathetertip and the pusher. As described above, however, a non-biasedconfiguration is generally preferred at the catheter tip for ease ofdelivery system retraction.

In another exemplary embodiment, shown in FIGS. 7A and 7B, dockingsection 242 of pusher 216 may comprise engagement means in the form of aset of fingers 244. Fingers 244 may define a pocket adapted forsurrounding the stent, as shown in FIGS. 7A and 7B. Referring now toFIGS. 8A and 8B, in yet another embodiment, docking section 342 ofpusher 316 may comprise pocket 340 in the form of an annular pocketbetween inner wall 341 and outer wall 343 adapted for insertion of thestent proximal end (not shown). Inner wall 341 may define a hollow orsolid cylinder, or may be in the form of fingers that insert within thestent. Outer wall 343 may be solid as shown in FIG. 8A and 8B, or may bein the form of outer fingers. As shown in FIG. 8C, another embodimentmay comprise a plurality of inner fingers 441 and outer fingers 443 thatdefine the inner wall and outer wall, respectively. Another embodiment,not shown, may comprise only inner fingers 441. Such inner fingers,outer fingers, or combination thereof may be radially biased outward.Although docking sections 242, 342, and 442 are described and shown inFIGS. 7A-8B with respect to pushers, similar docking sectionconfigurations may be provided for catheter tips.

The invention also comprises a method for pre-loading a stent deliverysystem, as described below relative to FIGS. 3 and 4. The methodcomprises loading at least compressed stent 14 and pusher 16′ withinouter sheath 12, including releasably engaging a portion of stentproximal end 30 with docking section 42 at pusher 16′ distal end 28,stent distal end 31 with docking section 42′ at catheter tip 20′proximal end 29, or a combination thereof. The method may includedisposing a portion of the corresponding stent end 30 or 31 within apocket 40 in docking section 42 or 42′.

The invention further comprises a method for deploying a stent inaccordance with the flowchart depicted in FIG. 5 and the drawings shownin FIGS. 3 and 4. The method comprises in step 100, introducing apre-loaded stent delivery system 10′ to a body lumen. Delivery system10′ comprises a compressed stent 14 having a proximal end 30 and adistal end 31, a pusher 16′ having a distal end 28, a catheter tip 20′having a proximal end 29 and attached to a central core 23 slideablydisposed within pusher 16′. At least one of pusher 16′ or catheter tip20′ have a docking section 42 or 42′ adapted to releasably engage thestent end over some length thereof, such as with pocket 40 and/or 40′within which the stent end is disposed. Outer sheath 12 overliescompressed stent 14, pusher 16′, and each docking section 42 and/or 42′.Next, in step 105, the stent delivery system is navigated to a desiredlocation for deploying stent 14, and finally, in step 110, outer sheath12 is retracted to deploy the stent from the outer sheath and fromdocking section 42 and/or 42′ into the desired location. Where cathetertip 20′ has a docking section 42′, the method may further compriseadvancing central core 23 and the catheter tip 20′ attached theretoprior to retracting sheath 12, to further facilitate release of stent 14from the docking section. Where pocket 40 has an end rim 44 that isradially biased outward and adapted to be inwardly compressed to gripthe stent end when loaded within outer sheath 12, as shown in FIGS. 3and 4, the method may further comprise the end rim expanding outwardduring evacuation of the stent from the pocket. Where, as is shown inFIG. 6, docking section 142 and/or 142′ comprise a reduced diametersection adapted for inserting within the end of stent 14, the method mayfurther comprise the stent expanding away from the reduced diametersection.

While the present invention has been described with respect to specificembodiments thereof, it is not limited thereto. Therefore, the claimsthat follow are intended to be construed to encompass not only thespecific embodiments described but also all modifications and variantsthereof which embody the essential teaching thereof.

1. A delivery system for delivering an endoluminal implant to a distaldeployment location inside a body lumen from a proximal access locationoutside the body lumen, the delivery system comprising: the implanthaving a proximal end and a distal end; a catheter comprising at leastone of a stabilizer, a catheter tip, or a combination thereof, thestabilizer having a distal end located adjacent the implant proximalend, the catheter tip attached to a central core slideably disposedrelative to the implant and having a proximal end located adjacent theimplant distal end; at least one of the catheter tip proximal end or thestabilizer distal end comprising a docking section adapted to releasablyengage a portion of the implant, each docking section comprising anengagement geometry for engaging the implant, and; a slidable sheathhaving an advanced position in which the sheath covers the implant and aretracted position in which the implant is exposed; each docking sectionengagement geometry comprising a flared engagement surface that extendsinside a short axial length of the implant or a pocket having abottleneck geometry.
 2. The delivery system of claim 1, wherein thedocking station comprises a member adapted to contact a completecircumferential portion of the implant.
 3. The delivery system of claim1, wherein the sheath cooperates with the docking section to keep theimplant in a compressed configuration, the docking section adapted torelease engagement of the portion of the compressed implant uponretraction of the sheath beyond a location at which the sheath at leastpartially overlies the docking section.
 4. The delivery system of claim1, wherein the docking section comprises a plurality of members eachadapted to engage a limited portion of the implant.
 5. The deliverysystem of claim 4, wherein the limited portion of the implant comprisesa partial circumferential portion.
 6. The delivery system of claim 4,wherein the docking section comprises a plurality of fingers.
 7. Thedelivery system of claim 6, wherein each finger has an end portion witha different cross-sectional area than a reminder of the finger.
 8. Thedelivery system of claim 7, wherein the different cross-sectional areacomprises an inward radial protrusion.
 9. The delivery system of claim1, wherein the endoluminal implant comprises a self-expanding stent. 10.A system for retaining a portion of a medical implant on a deliverymember until performance of a predetermined release action, the systemcomprising: the delivery member comprising an outer sheath and an innertubular member for engaging a portion of the implant, the sheath havingan advanced position in which the sheath covers the implant, and aretracted position in which the implant is exposed, the inner tubularmember having an axis and one or more flexible fingers, the one or moreflexible fingers having an unrestrained configuration with the sheath inthe retracted configuration in which the fingers are biased angularlyoutward from the inner tubular member axis, and a restrainedconfiguration with the sheath in the advanced configuration in which thefingers are adapted to engage a portion of the implant, each fingercomprising an end member having a different cross sectional geometrythan a remainder of the finger.
 11. The system of claim 10, wherein thedifferent cross sectional geometry of the end member comprises an inwardradial protrusion.
 12. The system of claim 10, wherein the predeterminedrelease action comprises retraction of the sheath.
 13. The system ofclaim 10, wherein the tubular member is adapted to engage the implant ata proximal end of the implant.
 14. The system of claim 10, wherein thetubular member is adapted to prevent axial movement of the engagedportion of the implant until the predetermined release action isperformed.
 15. The system of claim 10, wherein the delivery membercomprises a catheter comprising a stabilizer located adjacent theproximal end of the implant, wherein the tubular member is connected tothe stabilizer.
 16. The system of claim 10, wherein the delivery membercomprises a catheter tip located adjacent the distal end of the implant,wherein the tubular member is connected to the catheter tip.
 17. Thesystem of claim 10, wherein the implant comprises a stent.
 18. Adelivery system for delivering an endoluminal implant to a distaldeployment location inside a body lumen from a proximal access locationoutside the body lumen, the delivery system comprising: the implanthaving a proximal end and a distal end; a catheter comprising at leastone of a stabilizer, a catheter tip, or a combination thereof, thestabilizer having a distal end located adjacent the implant proximalend, the catheter tip having a proximal end located adjacent the implantdistal end and attached to a central core slideably disposed relative tothe implant; at least one of the catheter tip proximal end or thestabilizer distal end comprising a docking section adapted to releasablyengage a portion of the implant, the docking section comprising a pocketadapted to releasably contain a limited length of one end of thecompressed implant inserted therein, the pocket comprising an annularpocket having an inner wall located radially inward of the compressedimplant and an outer wall located radially outward of the compressedimplant, the inner wall and the outer wall both terminating at asubstantially same axial location relative to the implant.
 19. Thedelivery system of claim 18, wherein the docking section is integral tothe stabilizer or catheter tip.
 20. The delivery system of claim 18,wherein the docking section is an attachment to the stabilizer orcatheter.
 21. The delivery system of claim 18 wherein the dockingsection comprises a set of fingers comprising an inner set of fingersthat extend inside a short axial length of the stent, and an outer setof fingers that extend over a short axial length of the stent forming anannular region between inner and outer sets of fingers.
 22. A deliverysystem for delivering an endoluminal implant to a distal deploymentlocation inside a body lumen from a proximal access location outside thebody lumen, the delivery system comprising: the implant having aproximal end and a distal end; a catheter comprising at least one of astabilizer, a catheter tip, or a combination thereof, the stabilizerhaving a distal end located adjacent the implant proximal end, thecatheter tip attached to a central core slideably disposed relative tothe implant and having a proximal end located adjacent the implantdistal end; at least one of the catheter tip proximal end or thestabilizer distal end comprising a docking section adapted to releasablyengage a portion of the implant, the docking section comprising anengagement geometry for engaging the implant, and; a slidable sheathhaving an advanced position in which the sheath covers the implant and aretracted position in which the implant is exposed; the docking sectionengagement geometry comprising (a) a pocket having an outer wall locatedradially outward of the compressed implant and (b) a radial protrusionthat engages the implant.
 23. The delivery system of claim 22, whereinthe docking section radial protrusion protrudes inward from the pocketouter wall.
 24. The delivery system of claim 23, wherein the dockingsection pocket comprises a flared end rim radially biased outwardrelative to the compressed stent and adapted for the inward protrusionto releasably grip a limited length of the proximal end of the stent inpushing engagement therewith when the flared end rim is inwardlycompressed by the sheath to a non-flared diameter.